Traditionally, foundry cores have been produced by manually introducing sand impregnated with a core oil into the core box. After tamping, the cores are removed from the box and placed in an oven to cure the core oil. This method system of producing cores requires considerable time, and the cycle normally takes approximately two hours from the time the sand is initially placed in the core box until the core is removed from the oven. As a further disadvantage, the method is limited to less complex shapes or configurations, and in many instances wires are required to be embedded within the sand to maintain the configuration when the core is initially removed from the core box. Because of the oven heating, the system has a high energy requirement.
Automated methods for producing cores, known in the trade as "hot boxes", have also been used in the past. In the "hot box" method, sand impregnated with a heat curable resin is blown into the core box which is mounted on the machine. Subsequently, the core box is heated by gas fired burners to cure the resin binder and produce the core. While the "hot box" substantially reduces the cycling time for producing a core, over that of the previously described manual method, the "hot box" has a high energy requirement, and the intense heating causes worker discomfort, as well as possible distortion of the core.
More recently, a "cold box" system of producing foundry cores has been employed, in which the core box is charged with sand containing a resin binder that is cured through use of a catalyst gas. With the "cold box" method no heating of the core is required so that the system has extremely low energy requirements. However, the "cold box" systems that have been used in the past have had certain operational difficulties. As an example, the core box halves have been mounted on support plates which in turn are mounted for movement on fixed guide rods. The core box halves are normally lifted by use of a crane or hoist during installation of the core box halves to the support plates, and occasionally the guide rods may be damaged or bent as the core box halves are swung into position, with the result that the support plates cannot properly move between the open and closed position. The core box halves, when installed, may also be swung into contact with either the sand or gas head, resulting in damage to these structures.